Motormaster is in Voyager Wave 4, so it should be relatively easy to get from the usual online stores such as BBTS, Robot Kingdom, etc.
That said, the response from Hasbro did not specifically say we weren't getting Motormaster. It said they couldn't bring over the entire product range and we weren't getting any exclusive deluxes or exclusive leaders. It also said they were bringing voyagers and deluxes "next year". My take is that the whole response is a pretty weird thing to be seeing a few weeks before the mid-year toy sales, so I'd just wait and see for now.